2010-08-30

First day of school. There's a line a mile long -- backed up all the way to the freeway -- along the road we share with a couple of local high schools. I cleverly go down to the next exit, which turns out to be not so clever because there's a huge line there. There's another school on that hill. The clever rover driver forgot.

What with one thing and another, I'm about five minutes late. Which I think is no big deal, since there's no way we're driving.

Except, of course, that it turns out we are driving.

Great!

Not very far, though. I notice Dan's skeleton plan allocates only one hour for driving. "What can you do with one hour -- blind driving only?" he asks me. As part of the "baby steps" plan for getting back to normal, we're under an IMHO ridiculous temporary prohibition against using the PMA while driving.

"Not much," I tell him. "Especially since we can't go more than about five meters without slip checks, and we need the PMA for those."

"That's okay," Emily Eelkema interjects. "Five meters is fine. We just want to use all the motor control boards and actuate the steering and drive motors."

Well, fine by me. Actuating the steering and drive motors is what I'm here for. I plan a drive the easy way -- take the one we were prevented from doing on sols 563 and 567, and chop away all but the first 5m or so. Looks like we will do this drive, after all. One piece at a time.

2010-08-26

Opportunity's recent reset -- her little fainting spell -- is still a mystery. As with the previous, similar anomalies, we suspect that it's MTES-related, so there's no MTES this weekend. (However, we don't know that; it's just an educated guess. As John Callas later puts it, "The MTES just happened to be in Ford's Theater when Lincoln was shot. Twice.") But we're driving.

Or not. My plan is to resurrect the sol-563 drive, which never took place because Opportunity fainted before she could drive and therefore wisely decided to stay put instead. But John Callas swings by and sees it on my screen. He's nervous. "You think this is too ambitious?" he asks.

I don't. But he's getting flak from NASA HQ, which (the phase of the moon being what it is) is accusing us of proceeding too aggressively in the wake of a fault we can't explain. He goes away to worry about this, in a big meeting on the topic, while I smooth out some of the drive's rough edges.

We won't have quite as much drive time allocated for thisol as we did for 563, but Paolo works out a clever way to shave enough time off of the drive without compromising anything. We have it all ready to go when the anomaly meeting concludes.

The word: this reboot is, for some reason, worse than the last time something like this happened. (For some reason, we have no data products showing what happened immediately before the reboot -- a very unusual circumstance.) So we're doing nothing of interest this weekend. In particular -- you guessed it -- no driving.

This seems overcautious to me, but Justin Maki, who was in the meeting, provides the inside scoop. "Somebody brought up the point, 'What if you drove on without any further investigation and you never heard from Opportunity again? Could you tell the review board you did the right thing?' From there, it degenerated into a worry-fest." He grimaces. "I'm going to go get some lunch."

Worry-fest aside, the basic question is the right one to ask. Nobody thinks the investigation will turn up anything, since Opportunity was only executing a standard MTES sequence it had executed many times before. But the questions we'd face if we didn't do it ....

Okay, fine. This drive will go up someday, just not today. Meanwhile, I think Justin was onto something with that whole lunch idea.

2010-08-24

Yestersol's ambitious drive accomplished little. But it's not our fault: as part of our post-Purgatory paranoia, Opportunity has been driving with lower-than-usual current limits set on her drive motors. This is meant to detect when she's bogged down in a ripple (since the motors have to push harder than usual in that case), but in this case, they tripped during an otherwise perfectly nominal turn-in-place on a patch of outcrop.

This is the first time this has happened to me, but not, as it turns out, the first time it's happened. It's the fourth, and Jeff Biesiadecki's had enough. Thisol we're raising the current limits, and picking up the drive where we left off.

"It's spooky how close we are to the predicted position, though," Jeff muses as he looks at the situation in RSVP. We drove about 5m or so, and the rover really is right where RSVP said she would be at the turn-in-place point. Which is always nice, and something we've seen from our software over and over again. We really are quite good at this.

After lunch, I'm in the elevator with several other members of the uplink team. I push the button for the fifth floor and then realize I don't have time to stop off there. "You ought to be able to unpush the button," Jeff says. "Maybe it should toggle on and off."

"Yeah, but then people like me who push the button multiple times would have to be careful. We'd have to be sure to hit it an odd number of times."

"If you were in a hurry, you could toggle off other people's buttons and get to your floor faster," Jeff points out.

This is how I know I'm at JPL. I'm in an elevator, and we're redesigning the thing's user interface.

The sol goes well, though it takes longer than it should given that we're supposedly just picking up yestersol's drive sequence. (We can't resist the urge to tinker. That's the Elevator Lesson.) "I'm hungry," Beth Dewell says at 7PM or so. "I think I hate these late sols as much as Scott hates the early ones."

2010-08-23

The science team certainly seems to think so, and sent out congratulatory email to that effect. And Chris Leger has an argument that we're there: "Spirit's NAVCAMs can see horizon in every direction. If you were standing there, you'd say you were on the summit."

But the rear HAZCAM tells a different story. There's still a slight rise behind us, which peaks just a little way out -- less than ten meters, to my eye, probably more like five.

So we're there. Or we're not, depending on how you look at it. And maybe this isn't such a bad outcome, in its way: it gives us something to argue about, and more people who can plausibly claim to have been involved. I know I'm happy.

But I'm not on that rover; I'm back upstairs in the Land of Opportunity. I've been gone only a couple of weeks, but it feels a lot longer. Opportunity has spent almost the entire time IDDing outcrop, mixing in a couple of short bumps to sample additional tasty regions. But thisol it's time for us to move on, and we're striking out boldly. The whole drive doesn't cover that much distance, only 25m or so, but it's a long, winding one, a very rough "S" that wanders south and then north and then flattens out, hopping three ripples in the process. The point of all this meandering is to take us east toward Erebus Highway, which the scientists have decided, based on the outcrop we've just seen, that they definitely want a look at. (Cooper points out that this eastward jog will more or less maintain our radial distance from Erebus Crater, thus preserving the property that Erebus is always two weeks away. My theory holds!)

I can't refrain from asking the scientists what's so interesting aboutthe outcrop here. "Are you just starved, or does it taste good?" I ask Larry Soderblom, who at the moment is just a voice on the telecon. "I mean, are you guys just excited to see rock again, or is there actually something scientifically interesting about this rock?"

"Some of each," he laughs. "This outcrop is different from all the previous outcrop we've seen -- all of that stuff was exposed by impact events and maybe affected by them, so now we get to see the differences between that and non-impact-affected outcrop. Also we can check out the lateral variations in chemistry." Meaning, we get to see whether the water in this area was doing the same stuff as the water where we were before.

"Are you seeing any differences?"

I can hear the shrug. "We haven't seen enough of this stuff to tell. That's one of the reasons we want to get to the Erebus Highway."

"We're also gaining elevation as we head south," I muse. "Are we ever going to reach the shore of this sea? Maybe find areas that weren't affected by water after all?"

"Don't know," he admits. "There's a debate about whether we're going up or down in the stratigraphic sequence." I guess that should have occurred to me: just because this area is higher now, doesn't mean it was higher when the water was here. That sort of thing can happen to planets. Oh, well; that's why Larry's a geologist and I'm just a lowly Mars rover driver.

A lowly Mars rover driver who took Spirit to the summit of Husband Hill.

2010-08-21

We made OK progress, about what we expected or a little less. The bad news is, the summit's about 45m away. That's more than Spirit's been covering in a sol, so we probably won't make it thisol.

Not that that's going to keep us from trying. We have the advantage of being more or less atop the hill already, so the going is flatter and less sandy. We can do the first 20m of the drive blind, which is wicked fast (well, relatively speaking) and something Spirit probably hasn't been able to safely do since she started climbing. And that will help a lot.

"We might make it with three hours of drive time," Chris muses. "Hey, how much drive time do we have?"

"Two hours and forty-five minutes," Colette replies. Chris and I glance at each other -- and then turn back to Colette, wearing our most winning smiles. "I'll look into it," she says.

The planning meeting continues. As the scientists are winding down, Chris notices something in one of the NAVCAMs. He has Brenda project his screen on the front wall, where everyone can see it.

There in the distance is Home Plate.

Home Plate is one of the reasons we climbed Husband Hill in the first place. It's what's on the other side. From orbit it looks like a -- well, like home plate on a baseball diamond. It's a white, roughly pentagonal feature that might be an ancient Martian playa, an old lake where repeated evaporation events left an enduring salt crust. That, of course, would make it part of the "water story" of Gusev, so it's long been viewed as a high-priority science target.

It's exciting, of course, just to see our upcoming destination. What's even more exciting than that is the realization that WE CAN NOW SEE OVER THE HILL.

It's overwhelming, really. I don't know how to describe it. This isn't the summit, but it's the next best thing. When we started this project, Mars was so impossibly far away. Then we made it to Mars -- and the Columbia Hills (including Husband Hill) were so impossibly far away. Then we made it to the base of Husband Hill -- and the summit was so impossibly far away. And now we're within striking distance of the summit, proving it by looking over that hill.

Right now, Home Plate is just a whitish smear in the image. To me, it's one of the most beautiful things I've ever seen.

And I'm not the only one who thinks so. Alicia Fallacaro keys her mike. "Uh, Ray, Diana Blaney is requesting another PANCAM image ...." No need to say of what. We all crack up.

Having seen this sight, I'm even more okay with not making it to the summit. Paradoxically, I'm also even more inspired to make it. But whether we make it is going to be up to Colette and the rest of the team -- thermal, power, and so on -- as much as to the rover drivers. Can they give us the drive time we're going to need?

They try, I'll give them that. The answer changes through the day -- they find a way to give us thirty minutes, then have to take it back, that sort of thing -- but in the end it's the same sort of story as last time. They've already squeezed out as much time as they safely can. And as eager as we are to make it to the top, the golden rule with these rovers is: safety first.

So we probably won't make it this time. Maybe we'll have to wait until next week. Well, we've waited this long.

Our imminent arrival at the summit is starting to become a reality for everyone. Jim Erickson stops by to ask Chris and me about whether -- rather, when -- he should call a press conference to announce it. "I don't want to call it prematurely," he says, "but on the other hand, if we wait too long, we're going to get scooped by the bloggers." Yet another reason I'd rather have my job than his.

Chris and I work out the drive sequence. It's the first drive sequence we've built which, if it completes (please, oh, please!), will take us to the summit. In a flash of inspiration, Chris tells the rover to drive forward for the last few meters. We mainly drive backward -- the rover climbs a little better that way -- but traction isn't as big an issue now as it has been, and, as Chris points out, we're supposed to switch drive directions periodically anyway (to distribute wear and tear on the system).

But of course, that's not the real reason to drive forward at the end. The real reason is, in a word, style. Backing up onto the summit -- well, somehow it just isn't dignified. Would you drag yourself ass-first onto the peak of Everest? If we get really lucky, we'll end up with one of the front wheels poised on a rock, lifted slightly in a sort of planting-the-flag gesture.

Or not. As it turns out, the direction we'd be facing in if we drove forward will be bad for comm. So we have to change it back.

Undignified, maybe. But ready or not, summit, here we come.

[Next post: sol 583 (Opportunity sol 562), August 23.]

Courtesy NASA/JPL-Caltech. There it is: Home Plate, dead center, just visible in the valley beyond Husband Hill, with Von Braun Hill visible just beyond that.

Courtesy NASA/JPL-Caltech. We were so excited that we could see Home Plate, I'm not sure we even noticed this huge dust devil at the time. We must have, surely, but hell if I remember it today.

2010-08-18

Our previous drive went well. From here we can see what we think is the summit -- no more need to rely on uncertain orbital data for that, we hope -- and it's about 70m away.

I have this sol and, because we're in restricted sols now, just one more before I go back to Opportunity. And 70m is probably a little too far for us to make it in those two drives. Unless we can drive longer today ....

So I start campaigning for more drive time. I even try turning on the charm, which in my case is admittedly like turning on a rusty faucet in a long-abandoned house. And it's about as productive: no more drive time. We have to nap to keep the rover from overheating, and there's no science in the plan but the drive-support imaging, which obviously we can't cut.

We plan a drive that will probably make something like 30m progress (we command 50m but expect it to be cut short due to time), which will cut the remaining distance to the summit more or less in half, and leave it there. I'll just have to cross my fingers and hope Spirit has an unusually good day.

And if she doesn't, then, oh, well. So maybe someone else will have the actual experience of driving Spirit the last few meters up onto that rounded peak. It's just as well if the honor goes to one of the more regular Spirit drivers, who have done more than I have to actually climb her up this hill. I've got plenty of feathers in my cap already; it's getting a little crowded up there.

2010-08-16

Ray Arvidson says, "We'll be at the summit, if we're lucky, next week. Summit Two (this hill has two peaks, and that's the nearer and taller one) was about 120m from our last target, and we did about 30 over the weekend."

But someone else reports that Larry Crumpler's localization puts us only 45m away, half that distance. I ask Ashitey for the scoop, and he grins and rolls his eyes. "Nobody knows," he says.

"Did I just hear them say there's about 50m of uncertainty?"

"That," Ashitey agrees, "plus or minus 100."

It's rather like what happened as we approached the base of this hill. We were obsessed with reaching the base, and when we got there it was just a gradual slope -- a transition, but not an abrupt one, from plains to hillside. There was never a dividing line that said "You Have Now Reached Husband Hill." And now that we're reaching the top, it's the same thing: we're looking for a flag, forgetting that we came to plant it.

LTP finally comes on the line (they were knocked out by lightning, which destroyed the badge readers at their University of Arizona building) and speaks to the point, though they don't offer much clarity: according to them, the summit is either 50m or 70m away, at an azimuth of either 104 or 140, depending on whose localization you believe (Larry Crumpler's or Ron Li's). Ashitey says he wants the summit to be about 300m away, since he's going out of the country for a week and doesn't want to miss the goal he worked so hard for. But while there's uncertainty in the numbers, there's not that much uncertainty. Sorry, Ashitey.

Well, we'll drive at 120 today; that'll be close enough for now. And we're only going 20m, because that'll take us to a ridge we need to see over in order to continue.

Ashitey does most of the work as Ashley Stroupe -- another Mob/IDD team member training for the RP job -- looks on. Then Ashley watches and works with me as I do my RP-2 thang.

She's pretty sharp and seems to be coming up to speed well. Which is what I tell Frank when he asks me. "She seems kinda nervous, but I think she's gonna be fine," I tell him.

"Nervous is good," he says. "I worry more about the ones who aren't nervous. Like, I think, 'I remember how nervous I was when I was first doing this. How can you not be nervous?'"

Which is funny and true. If you're not nervous about taking this job on, you're not taking it seriously enough.

Later, I have Ashley walk through the sequence for me, as a way of ensuring she understands everything in it. Then -- what the hell -- she understands everything anyway. "So you do the CAM walkthrough," I tell her.

[1] One of the pleasures for me in reviewing these notes, five years after the fact, is to see the first appearance of people who would later become rover drivers -- good ones. It happened with Jeng, and with Ashitey, and with Paolo, and now it's happened again with Ashley. Ashley, as you might know, is the lead RP for Spirit -- and I hope Spirit gives her some work again soon, when Spirit wakes from her winter hibernation.

Courtesy NASA/JPL-Caltech. The way ahead. So close to the top that we can taste it -- and yet we're going to have to restrain ourselves to slogging ahead, one little bite of that distance at a time.

2010-08-13

I'm back on Spirit. But what with the MRO launch usurping some of our comm passes, and the fact that we're in restricted sols anyway, we're planning so far ahead that we've already planned thisol. But it hasn't executed yet, so there's no data to plan a drive for the weekend. So they don't need me.

What they need is a way to fill up the downlink. This is not a problem I've been used to, over in the Land of Opportunity, but here in the Spirit World they're downlink-rich right now. They're getting something like 270 Mbits downlinked in the next plan alone.

One of the things they come up with to fill up the bits: more dust devil movies. What the heck, they're cool -- that's even how they get sold. "I just like that the scientific rationale is 'it's really cool,'" chimes in one of the scientists on the line. He's not quite objecting, but of course we do always want to use these rovers to best advantage. But quick-witted Diana Blaney retorts, "OK, I'll give you a scientific rationale. We're clearly entering a period of increased dust devil activity, and this will give us better data for statistical analyses." There's applause: Diana just solidly saved an observation we all wanted to do anyway.

And as another scientist points out: we're one and a half years into this mission, and we have a sol that's neither power- nor data-limited. These rovers are supposed to be dead. But obviously, nobody told them.

2010-08-04

"Wow, Scott, you're batting a thousand this week." Jeff Favretto is right: I'm on a roll and I know it. Once again, Opportunity is right where she's supposed to be, peeking over (and actually perched on) a small ripple, with a patch of outcrop just on the other side, lying dead center in the next trough.

The science team, having been long denied any rock targets to sink the rover's teeth into, wants us to put 'em right on top of it. So that's our plan. We could head straight for it, but if we did that we'd be crossing the ripple somewhat obliquely, and the right side would pass through a patch of relatively soft-looking stuff, which can hurt our precision. So we settle on a different approach, turning left and scooting directly across the ripple where we are, then turning right and heading down the trough onto the outcrop.

And now we have naming of parts. Larry asks for a name for the target we're trying to get into our IDD workspace in this drive. I point out that from overhead the outcrop looks like an ice-cream cone -- we're going to be driving along the cone and parking with the scoop in the IDD work volume. What I didn't realize was that Larry was asking one of the scientists to suggest a name. He suggests "Mound" -- the target being slightly raised, like a pitcher's mound.

"Yeah, that's original," I say off-mike, to the amusement of listeners in the room. "Let's go with that." (Later, Larry agrees with me, and they end up naming the IDD targets with an ice-cream theme.)

Just before the walkthrough, Jeng and I get concerned about the precision of the drive. It's only Wednesday, so they can bump on Thursday if we don't get this right, and still be able to IDD over the weekend. But I want to get it right -- for the sake of my pride, and because this is my last Opportunity shift for a while, and, oh yeah, because sols cost a million dollars a day and my job is to make them go as well as possible.

Our concern is the first part of the drive, where we're crossing Fudge Ripple. If we're going to slip appreciably, we're going to do it here, and the rest of our drive depends on that part going correctly. After some discussion, we end up turning on visodom for that segment of the drive. Because of the leftward turn, we can't look back at our tracks, but there's a whole bunch of juicy outcrop in this area, so we point visodom at that instead. If it doesn't converge, we're no worse off than if we weren't using visodom at all, and if it does converge, it will help the drive go a lot better. So we'll probably win, and can't lose. Unless one of the dozen or so last-minute changes completely screwed something up.

I guess we'll see.

After I return to the Spirit World, Opportunity will spend a few days, possibly a week, IDDing this outcrop. Then she'll stow and continue toward Erebus.

She'll probably make it to Erebus in about two weeks. Or not. I've been joking that Erebus is a sort of anti-Wopmay and will always be two weeks away. I'm not actually sure that I'm joking, come to think of it. Last week or so, we thought Erebus was a little less than two weeks away, only to find that our position in the orbital mesh was wrong. The corrected position put us 75m farther from the crater -- adding another two or three days of driving, and putting us back to a full two weeks. See? If necessary, the whole planetary surface will move in order to keep Erebus two weeks away. And of course, as long as we sit here at the outcrop, Erebus will remain two weeks away.

I elucidate this theory for Jeff Favretto, who agrees sagely. "So you're saying it's some sort of Martian Groundhog Day. Every day you come in and plan pretty much the same drive, and when you come back the next day, you're still as far away as when you started."

2010-08-03

At the SOWG meeting, Larry Soderblom asks if one of the RPs would give an assessment of yestersol's drive and give them a preview of what we're planning to do thisol. "Yestersol went perfectly," I reply, "and we're gonna do it again."

"All right, short and sweet," chuckles Larry.

Yestersol's drive did go perfectly -- textbook. As I expected, we can see that the jumbly bits at the far end of the drive are benign ripples, now that we're right on top of them.

So thisol we're going to drive over them, proceeding another 25m or so along this trough. At the end of that distance is another discontinuity -- probably just a small rise, but large enough that we can't see over it. Beyond that is a sweet-looking patch of outcrop. Off we go.

As I'm sequencing, I overhear Kurt telling Jeff Favretto something. Jake Matijevic has worked out that the drive motors on both vehicles have about 10 million revolutions. They were designed for 2.5 million but qualified for 4 times that, so we're right about at their limits.

Well, I always said we were going to drive these things until the wheels fell off. I guess we'll see how soon that's going to happen.[1]

Footnotes:

[1] Five years later -- and many kilometers, and many millions of revs on the motors -- we're still going.

2010-08-02

"It's way too early to be driving rovers," mutters Jeff Favretto. I must agree. It's 07:00, and it's a tight sol -- meaning our uplink is just a few hours away -- so we have to get a lot done, with little room for error.

Fortunately, Mars is kind to us thisol. The previous drive didn't go quite where it was meant to, but it made good progress and left us at the entry of a fairly wide trough that extends for another 25m or so. At that point, it's hard to tell what happens; there are ripples blocking our path, but they're not too scary-looking. Still, we don't want to try to cross them thisol. So this will be a simple, straight drive, about 24m down the trench. We'll stop after a few meters to PCAM an outcrop ("Zurich") just in front of us, but otherwise there's not much special about it.

I'm pretty well done with the sequence in maybe four hours, leaving me time to handle another of Susan Kurtik's tour groups. This one I take up into the SOWG room, since there's a moderate-fidelity full-scale rover model in there now. This model is named "Bubba." I am not making this up.

Just before Cooper delivers the sequence, I realize we've been making a mistake. The new-style driving, where we punctuate the drives with 40cm slip checks every 5m or so, has a flaw: if the lowest-level visodom-update sequence doesn't make it on board, our sequence won't detect that. Instead, it will blithely believe that the slip test passed and keep driving. Murphy's Law says this will happen on a sol where we really do get stuck, so I persuade Cooper to make the easy fix, inserting a single call to that helper sequence in our drive backbone. The command that invokes that helper is told that it should abort the backbone sequence if the target sequence isn't on board, which will mean that we'll cancel the drive if the helper is missing. That's the safe and logical thing to do, and that's the end of that.

Or so you'd think. Speaking of Murphy's Law ....

At the point where the backbone calls the helper, no special visodom pointing has yet been set up. This means that that call to the helper will do visodom using the HAZCAMs. None of this matters in itself; the result isn't used anyway, we're just invoking the helper for the side effect of canceling the drive if the helper is missing. The rest of the drive properly sets up to do visodom using the NCAMs instead. But it's this switch from one set of cameras to the other that worries me. That's supposed to work, and I think it's even been tried, but I don't really know that it works. So just out of an abundance of caution, I call Mark Maimone's voice mail, describe the situation, and ask him to call me back if there's a problem with this.

I don't hear back from him. Until -- just as the CAM ends, my phone rings. It's Mark. And it's bad news. I'm right that what I describe is supposed to work. It's even been done a few times, and worked. But once, it didn't work -- subsequent NCAM updates in the same drive started failing for no apparent reason. Mark was never able to track down the bug, and he isn't sure it's because of the camera switching. But just in case, he recommends we fix it.

Oh, lovely. I really, really hate to do this; we had such an early start, and everybody thought they were just about to leave. And this is going to delay us for, like, an hour. I only have to make a minor change, but then Cindy has to spend an hour turning all the cranks that need to be turned in order to produce the uplink.

But it has to be done.

So we do it.

Oh, but the fun's not over yet. After we've rebundled and reviewed the changes, another thought occurs to me. In the backbone sequence, we're turning visodom off (it's turned on as needed during the slip checks). This means that the first time the helper is called, it's called with visodom off. It will still do a nav map update -- and will have the side effect of checking for the sequence's existence -- but not a visodom update. If we need it to do a visodom update, we have to turn visodom on. Which is going to mean another minor change to my sequence, followed by another hour's delay for the entire team ....

The sinking feeling starts, I turn to say something, and -- wait a minute. If the first call to the helper is being performed with visodom disabled, so that it isn't doing a visodom update, then we have no reason to think it will interfere with the actual visodom updates during the drive. Not only do we not need to rebundle again, we didn't need to rebundle the first time.

I think about whether to say anything about this. Either version of the sequence, I now realize, will do the same thing, so it makes no difference to the rover. However, all else being equal, we should go with the simpler thing -- that is, revert to the first version. But there's another consideration. Doing this job is exhausting any time, but it's worse when we start at 07:00. Right now the team is tired, but proud of themselves for sticking to their posts and doing the right thing.